Computer keyboards (hereafter, keyboards), for entering data and commands into a computer, have many different design shapes and sizes. Most current keyboards require the user to exert a downward force on a key to generate a key event. Given that keyboards have become so widely used by so many people today, and that many people spend a significant amount of time operating a keyboard each day, serious health conditions associated with keyboard use are now commonplace.
In general, these health conditions are referred to as repetitive strain injuries (RSI). They are triggered by small, prolonged and repetitious strains in the hands and arms of a keyboard operator. These strains can cause pain, weakness, or numbness in the keyboard operator's muscles, tendons, and nerves of the neck, shoulder, forearm, and hand. The sudden stop of a keystroke at the end of its downward motion, for instance, can aggravate RSI symptoms.
Proper typing form dictates that it is best to keep one's hands elevated above the keyboard and lightly press each key. Many keyboards today encourage poor typing form by providing wrist rests, which are pads intended to support one's wrists while typing. This typing position leads to RSI conditions such as carpal tunnel syndrome. Keyboards also often include kick stands mounted on the underside. These kick stands are typically located toward the rear of the keyboard with respect to the operator. When fixed in place, the kick stands elevate the rear side of the keyboard. This orientation encourages the operator to flex his hand upward (i.e., dorsiflexion) to reach the keys, while possibly resting his palms on a wrist rest. This hand position, too, is known to aggravate RSI symptoms, and has been correlated with carpal tunnel syndrome cases.
Keyboard manufacturers have responded to increasing incidences of RSI with ergonomic keyboards. Although helpful, these ergonomic keyboards do not alleviate a primary cause of RSI conditions, that is, the repetitive strain of pressing the keys. One manufacturer has a keyboard requiring only a soft touch to activate keys. Notwithstanding, the light taps required to activate the keys can still inflame and worsen RSI symptoms. Also, to achieve the soft-touch activation, the keyboard surface is generally flat, and, with the exception of small raised dots on some keys, provides little tactile feedback for the operator to determine where his hands are located on the keyboard. Consequently, the fingers of the operator can drift across the keyboard and activate the incorrect keys.
Most keyboards comprise moving parts. Each key of the keyboard typically includes three or more physically moving parts: the key housing, the spring, and the actuator. Moving parts are susceptible to wear and necessitate crevices between the keys to enable the keys to operate freely. These crevices, however, make the keyboards especially vulnerable to liquid spills and to particles of food and dirt.
Traditional keyboards with moving parts also make a mechanical clicking sound when the operator presses the keys. This clicking sound results from the physical key movement and sudden stop of downward motion when the key is fully depressed. Although this audible feedback may help the typist, the sound can become a nuisance, for example, where multiple operators are typing in close proximity to each other, or when a customer of a call center hears a computer operator typing while talking to her on the telephone. Keyboard manufacturers have recognized this problem and offer quiet keyboards, but even these quiet keyboards emit a clicking sound, however faint, when the keys are pressed.
Most keyboards also become difficult to use in low-light conditions. Because many computer users need to look at the keys often to type accurately, when the lighting is insufficient to see the keys clearly, the operator tends to make typing mistakes more frequently, thereby reducing his effective typing speed and increasing frustration. One currently produced keyboard shines light between its keys. The light coming from between the crevices, however, is insufficient to enable the operator to discern the characters represented by the keys. Keyboard clip-on lights are available, but their use is awkward and not well-suited to the varying shapes and styles of keyboards.